The interpretation of the indirect inspection data is a critical factor in conducting a successful ECDA process. The data must be validated, discrepancies must be resolved, and indications must be identified, classified and prioritized, in order to select the sites for direct examinations.

This paper analyzes the various types of data provided by the indirect inspection tools and especially their interrelation. Additional types of indications related to AC and DC interference are also discussed. “Threat related” classification and prioritization criteria, as successfully applied on more than 50 gas pipelines in Ontario, are presented and rationalized. Possible error scenarios resulting from neglecting the interaction between various types of indications are developed from existing sets of data.

Subject
Holidays, Prioritization, Indirect inspection, External corrosion direct assessment, Voltage, Pipelines, Tools, Current densities, AC voltage gradient, DC interference, Electric potential, Risk management, Surveys
Keywords:
External corrosion direct assessment, ECDA, close-interval potential survey, CIPS, close-interval survey, CIS, DC voltage gradient, DCVG, AC voltage gradient, ACVG
© 2011 Association for Materials Protection and Performance (AMPP). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of AMPP. Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
2011
Association for Materials Protection and Performance (AMPP)
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